The Internet Corp for Assigned Names and Numbers is proposing that three new top-level domains be added to the internet, but plans currently under discussion call for a limited roll-out that would focus on niche markets.

In a document published over the weekend, ICANN president Stuart Lynn asks for public input on recommendations that three "sponsored" TLDs be added to the internet, and that proposals be solicited from interested parties.

A sponsored TLD is one with a narrowly defined registrant base, such as .pro or .aero, which target certified professionals and the aerospace industry respectively, as opposed to unsponsored TLDs, such as .com or .info, which are open to anybody.

Lynn said experiences with the last batch of new TLDs, approved two years ago, "seem to indicate that sponsored TLDs can be added smoothly and with little fanfare." He said they "have generated relatively few problems" and "can fill easily demonstrable community needs".

In the document, Lynn also opens the floor for proposals to create a taxonomy, or category structure, for the domain name system, into which all future TLDs can easily be slotted. He said he has heard arguments for and against such a taxonomy versus an open marketplace with no such restrictions.